Mechanic says car needs transmission on 2001 Ford Explorer

The O/D light came on just in normal driving and mechanic says to replace transmission.

Asked by for the 2001 Ford Explorer
what is trans doing
2 more answers , 2 more comments
Definitely worth a second opinion...
When the OD light comes on and flashes there is a problem in the transmission. It could be something simple like a bad selenoid or major transmission problem. Take it to a transmission shop that has a good reputation, and have the transmission codes read. This will telln you what cost you are looking at.
The mechanic did not tell me the code but said it would cost $2200.00-$2400.00
The diagnostic trouble codes go a long way to help the technician diagnosing a transmission concern, but keep in mind, if the technician removed the transmission pan and found heavy metal debris from some of the many moving components, a replacement or over-haul is still necessary. A failed $3.00 washer in a transmission could come apart and take out thousands of dollars of components. I recommend asking questions as to why the shop come to the conclusion and what other options are available.